Hydrocarbon reservoirs are pressurized due to the weight of rock and/or interstitial fluid in the formations above the reservoir. When drilling for hydrocarbons, such as oil or condensates, a column of fluid of sufficient density is used to balance or exceed the reservoir pressure to prevent the uncontrolled release of hydrocarbons to the atmosphere. However, when suitable equipment has been installed in the well and on the surface of a well to test or produce the hydrocarbons, it is desirous to bring the well into production. This is achieved by reducing the density and hence the hydrostatic pressure of fluid holding the hydrocarbons in place such that the reservoir pressure exceeds that of the column of fluid above it and hydrocarbons flow from the reservoir to the surface. Typically, when production is due to take place, a specialized tube and equipment is placed in the well bore through which the hydrocarbons flow and which, for purposes of the present disclosure, is referred to as the “production string.”
The operation of bringing production online can be made more difficult by one or more of the following problems:                Reservoir pressures decrease with time when under production;        Formation water can be produced that may increase the density of the fluid in the production string sufficiently to stop a well flowing; and        Brines used in the drilling process may try to flow back up the production string and increase the pressure holding the hydrocarbons in place.        
There are several known methods for initiating well production or increasing production.
A gas can be injected into the production string at depth to mix with the oil and thereby reduce the resultant density of the fluid. Nitrogen, carbon dioxide and hydrocarbon gases have all been used. The disadvantage of this method is that it requires trained people, a supply of the gases, and a significant amount of complicated equipment.
Another method is to introduce electric or mechanical pumps into the wellbore to pump the oil to the surface. The disadvantage of this method is again cost, and the longevity of pumps operating deep in the wellbore is not high.
A further method is to inject water or gas into the reservoir at a different point to increase the pressure in the reservoir. The downside of this method is that separate wellbores have to be drilled and injection equipment must be installed at great cost.